General tools
Percentage calculator
The three everyday percentage questions, answered as you type. Everything runs in your browser - nothing is uploaded.
Percentage of a number
X is what percent of Y
Percentage change
How it works
This calculator covers the three percentage questions that come up most often. "What is X% of Y" finds a part from a whole - a discount, a tax, a tip. "X is what percent of Y" works the other way, turning a part and a whole into a percentage. "Percentage change from X to Y" tells you how much a value rose or fell, which is the right tool for a price increase, a pay rise, or a drop in a metric.
Type into any field and the answer updates instantly. Everything runs in your browser, so nothing is sent to a server, and there is no rounding surprise: the result is the exact arithmetic, shown to a sensible number of decimals. If you leave a field blank or enter something that is not a number, that row simply waits until it has what it needs.
Example. To find 15% of 80, use the first row: enter 15 and 80 and you get 12. To check that 12 is what percent of 80, the second row reads 15%. If a price went from 80 to 92, the change row shows a 15% increase.
FAQ
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For 15% of 80 that is 80 x 15 / 100 = 12. The first row does this for you - enter the percentage and the number and read the answer.
What is the difference between percentage change and percentage difference?
Percentage change has a direction: it measures how much a starting value grew or shrank to reach an end value, so going from 80 to 92 is a +15% change. This calculator computes change relative to the first (starting) value, which is what you want for prices, salaries, and trends over time.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value, and multiply by 100: (new - old) / old x 100. A positive result is an increase and a negative result is a decrease. Dividing by zero (an old value of 0) has no defined percentage, so that case is left blank.
Is my data sent anywhere?
No. Every calculation runs locally in your browser with plain JavaScript. Nothing is uploaded, logged, or stored on a server.